Bushing-restrictor

ABSTRACT

A bushing-restrictor having a plurality of axially spaced circumferential grooves in its outer periphery, connected together by axial slots extending through alternate lands between the grooves on opposite sides of the bushing-restrictor diametrically across from each other.

United States Patent [72] Inventor James N. Tootlc Kalamazoo, Mich. [211Appl. No. 806,531 [22] Filed Mar. 12, 1969 [45] Patented Sept. 7,1971[73] Assignee Pneumo Dynamics Corporation Cleveland, Ohio {54]BUSHING-RESTRICTOR l 1 Claims, 5 Drawing Figs [52] 11.8. C1 92/153,92/165, 308/240 [51] lnt.Cl ..Fl6c 37/00, Fl6c 29/00 [50] Field ofSearch 92/86, 163, 153,155, 88,165,168-171;308/240,76, 17;

[56] References Cited UNITED STATES PATENTS 5,024 3/1847 Eddy .1 123/193C 221,223 10/1879 Epping 123/193 C 1,386,219 8/1921 Archer 308/771,438,915 12/1922 Howe 123/418 Primary Examiner- Martin P. schvvadronAssLslantExaininer-Allen Ostrager Attorney-Stephen M. Mihaly ABSTRACT:bushing-restrictor having a plurality of axially spaced circumferentialgrooves in its outer periphery, connected together by axial slotsextending through alternate lands between the grooves on opposite sidesof the bushingrestrictor diametrically across from each other.

BUSHING-RESTRICTOR BACKGROUND OF THE INVENTION The present inventionrelates generally as indicated to a bushing-restrictor and moreparticularly to a bushing-restrictor having novel means for providingrestricted flow past the rod end of an actuator to cool the same.

High-temperature nozzle actuators for afterburners and the like usuallyrequire supplemental cooling at the rod end of the actuator fordependable, trouble-free service. It has been common practice to effectsuch cooling by providing a stack of orifice plates in the rod end ofthe actuator that permit an allowable cooling flow therethrough, butsuch orifice plates have not proven to be entirely satisfactoryespecially where weight and space requirements are a factor, as inaircraft and space applications, since the orifice stack and pressurevessel therefor are relatively large and heavy.

SUMMARY OF THE INVENTION With the foregoing in mind, it is a principalobject of this invention to provide a relatively inexpensive combinationbushing and restrictor of lightweight and compact construction whichboth supports the actuator rod and permits restricted flow through therod end of the actuator cylinder for cooling the same in a novel manner.

Another object is to provide such a bushing-restrictor which precludespassage of any large contaminants therethrough.

Still another object is to provide such a bushing-restrictor which isfree-floating thereby permitting hydraulic pressure at the rod side ofthe actuator cylinder to urge the bushingrestrictor into engagement withthe adjacent packing to compress the same thus assisting in maintaininga fluidtight seal.

These and other objects of the present invention may be achieved byproviding the bushing-restrictor with a plurality of axially spacedcircumferential grooves in its outer periphery, connected together byaxial slots extending through alternate lands between the grooves onopposite sides of the bushing restrictor diametrically across from eachother. A slight diametral clearance between the inner end of thebushingrestrictor and the adjacent wall of the actuator prevents entryof any large contaminants into the grooves which might otherwise clogthe same.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail a certain illustrativeembodiment of the invention, this being indicative, however, of but oneof the various ways in which the principles of the invention may beemployed.

BRIEF DESCRIPTION OF THE DRAWING FIG. 2 is an enlarged side elevationview of the bushingrestrictor shown in FIG. I;

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 there is a schematicshowing of a hydraulic actuator l of a type commonly used inafterburners and the like, comprising an actuator cylinder 2 having apiston 3 axially reciprocable therein for reciprocating a piston rod 4which projects through an elongated end portion 5 of reduced diameter.The opposite or head end 6 of the cylinder 2 is closed by an end capassembly 7.

Contained within the rod end portion 5 surrounding the piston rod 4 is apreferred form of bushing-restrictor 10 in accordance with thisinvention which not only performs the usual bushing functions ofmaintaining the piston rod 4 coaxial FIG. 3 is a longitudinal sectionthrough the axial slots in the with the cylinder bore 11 andtransferring the side loads incurred by the piston rod 4 to the cylinder2, but also permits flow of a small portion of the hydraulic fluidsupplied to the rod end of the cylinder through the rod end portion 5 toprovide effective cooling thereof which is necessary for effectiveoperation of the actuator when used in high-temperature applications ina manner to be subsequently fully explained.

The details of construction of the bushing-restrictor 10 which permitssuch restricted flow can readily be seen in FIGS. 1-5, wherein aplurality of axially spaced annular grooves 15 are shown provided in theouter periphery of the bushing-restrictor sleeve 24, connected togetherby axial slots 16 and 17 extending through alternate lands 18 and 19between the grooves 15 circumferentially spaced apart from each other,preferably on opposite sides of the bushing'restrictor diametricallyacross from each other. The outer diameter of the lands 18 and 19 issubstantially the same as the inner diameter of the bore 20 in the rodend portion 5 of the cylinder 2 so that fluid cannot pass over thelands, but the OI) of the inner end 21 of the bushing-rcstrictor 10 isslightly less than the ID of the bore 20 to provide a slight diamctralclearance 22 therewith to permit hydraulic fluid to enter the enlargedgroove 23 adjacent thereto while restricting the passage of any largecontaminants which may be container. in the fluid, thus acting as anedge filter. The fluid flowing past the edge filter 22 into the enlargedgroove 23 flows through an axial slot 16 into the next groove 15 whereit flows around the bushing-restrictor to the opposite side and thenpasses through the next slot 17, and so on through the slots from grooveto groove for increased circulation of the fluid through said grooves. A

Adjacent the last land 19 there is provided another groove 26 of greateraxial extent then the grooves 15 to establish communication with adischarge passage 27 in the rod end 5 for return of the cooling fluid toa reservoir (not shown). Although the number and size of annular grooves15 and axial slots 16, 17 may be varied as desired depending upon theamount of cooling flow desired, a bushing-restrictor having l7 annulargrooves 0.028 inch wide and 0.035 inch deep, and 18 slots approximately0.0l4 inch wide and 0.020 inch deep provides an allowable cooling flowthrough a 1.036 inch diameter bushing-restrictor. The enlarged groove 23may be 0.125 inch wide and 0.067 inch deep, whereas the elongated groove26 may be 0.250 inch wide and 0.035 inch deep, and there may be aclearance 22 of approximately 0.004 inch between the inner end 21 of thebushing-restrictor and the bore 20. Exert for the radial holes 30through the bushing-restrictor sleeve 24 in the region of the groove 26which provide for lubrication of the piston rod 4, the sleeve 24 isdesirably imperforate as shown.

As shown in FIG. 1, a suitable packing 31 is disposed in the rod endportion 5 outwardly of the bushing-restrictor 10 which may be compressedto the desired extent and held in place by a suitable retainer 32. Anout-turned flange 33 on the outer end of the bushing-restrictor 10 isadapted to engage a stop shoulder 34 on the wall of the bore 20 toprevent the bushing-restrictor from being pushed into the cylinder 2 bythe packing 31. However, the bushing-restrictor 10 is substantiallyfree-floating, whereby the hydraulic fluid admitted to the rod end ofthe cylinder 2 through the port 35 will urge the bushing-restrictortoward the packing 31 to further compress the same and thus preventloosening of the seal and leakage therepast even should the packingshrink with age. Fluid is permitted to flow into and out of the head end6 of the cylinder 2 through a port 40 therein. If desired, a portion ofthat fluid may be used to cool the piston rod 4 internally by making thepiston rod hollow as shown.

From the above discussion it can now be seen that the bushing-restrictorof the present invention permits a small allowable cooling flow to passthrough the rod end of the actuator without requiring the usualmultiple-stacked orifice system, at a substantially savings in space andweight. The bushingrestrictor is of a relatively simple one-piececonstruction which may be readily installed in the actuator, and becauseof its free-floating nature, it will be urged against the adjacentpacking by the fluid in the cylinder to assist in compressing thepacking and thus help prevent leakage therepast.

l, therefore, particularly point out and distinctly claim as myinvention:

1. A fluid actuator comprising an actuator cylinder, a piston axiallyreciprocable in said cylinder, means for permitting fluid to flow intoand out of opposite ends of said cylinder for reciprocating said piston,a rod projecting from said piston through a bore in one end of saidcylinder, and a bushingrestrictor contained in said bore surroundingsaid rod, said bushing-restrictor comprising a sleeve having a pluralityof axially spaced annular grooves in its outer periphery, the landswhich define said grooves therebetween having a close sliding fit insaid bore, and axial slots extending through said lands, said axialslots through adjacent ones of said lands being circumferentially offsetfrom each other and ofa size to permit a small portion of the fluidcontained in the rod end of said cylinder to circulate through andaround said grooves before discharging to the adjacent groove forcooling said rod end, the inner end of said sleeve having an outerdiameter which is slightly less than the inner diameter of said bore toprovide a slight diametral clearance which acts as an edge filter forpermitting the fluid in the rod end of said cylinder to pass into theadjacent groove in said sleeve while restricting the passage of anylarge contaminants contained in the fluid, said sleeve having anadditional groove adjacent said inner end which is slightly deeper thansaid plurality of axially spaced annular grooves for receiving the fluidpassing through said diametrical clearance, said sleeve having stillanother groove adjacent the outer end of said sleeve which is axiallylonger than said plurality of axially spaced annular grooves, and radialholes extending through said sleeve communicating with said axiallylonger groove for lubricating said rod.

2. A fluid actuator comprising an actuator cylinder, a piston axiallyreciprocable in said cylinder, means for permitting fluid to flow intoand out of opposite ends of said cylinder for reciprocating said piston,a rod projecting from said piston through a bore in one end of saidcylinder, and a bushingrestrictor contained in said bore surroundingsaid rod, said hushing-restrictor comprising a sleeve having a pluralityof axially spaced annular grooves in its outer periphery, the landswhich define said grooves therebetween having a close sliding fit insaid bore, axial slots extending through said lands of a size to permita small portion of the fluid contained in the rod end of said cylinderto flow through and around said grooves for cooling said rod end, andradial holes extending through said sleeve communicating with one ofsaid grooves for lubricating said rod.

3. A fluid actuator comprising an actuator cylinder, a piston axiallyreciprocable in said cylinder, means for permitting fluid to flow intoand out of opposite ends of said cylinder; for reciprocating saidpiston, a rod projecting from said piston through a bore in one end ofsaid cylinder, and a bushingrestrictor contained in said boresurrounding said rod, said bushing-restrictor comprising a sleeve havinga plurality of axially spaced annular grooves in its outer periphery,the lands which define said grooves therebetween having a close slidingfit in said bore, said sleeve having another groove adjacent the innerend thereof In direct fluid communication with the rod end of saidcylinder, and axial slots extending through said lands between saidaxially spaced annular grooves, said axial slots through adjacent onesof said lands being circumferentially offset from each other and of asize to permit a small portion of the fluid entering said additionalgroove adjacent the inner end of said sleeve from the rod end of saidcylinder to flow through and around said grooves before discharging tothe adjacent groove for cooling said rod end.

4. The fluid actuator of claim 3 wherein said axial slots throughalternate ones of said lands are located on opposite sides of saidsleeve diametrically opposite each other to maximize the circulation offluid through said annular grooves.

5. The fluid actuator of claim 3 wherein the inner end of said sleevehas an outer diameter which is slightly less than the inner diameter ofsaid bore to provide a slight diametral clearance which acts as an edgefilter for permitting the fluid in the rod end of said cylinder to passinto the groove adjacent the inner end of said sleeve while restrictingthe passage of any large contaminants contained in the fluid.

6. The fluid actuator of claim 5 wherein said groove adjacent the innerend of said sleeve is slightly deeper than said axially spaced annulargrooves for receiving the fluid passing through said diametralclearance.

7. The fluid actuator of claim 3 further comprising a packing, and meansfor retaining said packing within said bore outwardly of said sleeve,the outer end of said sleeve having an out-turned flange thereonprojecting radially outwardly beyond said lands, and said bore having ashoulder adapted to be engaged by said out-turned flange to prevent saidbushingrestrictor from being forced into said cylinder by said packing.

8. The fluid actuator of claim 7 wherein said bushingrestrictor issubstantially free-floating within said bore, whereby the fluid in saidrod end of said cylinder acting on said bushing-restrictor urges saidbushing-restrictor toward said packing to compress the same and thusprevent loosening of the packing and leakage therepast.

9. The fluid actuator of claim 3 wherein said sleeve is substantiallyimperforate.

10. The fluid actuator of claim 5 wherein said diametrical clearance isapproximately 0.004 inch.

ll. The fluid actuator of claim 2 wherein said one groove is adjacentthe outer end of said sleeve.

1. A fluid actuator comprising an actuator cylinder, a piston axiallyreciprocable in said cylinder, means for permitting fluid to flow intoand out of opposite ends of said cylinder for reciprocating said piston,a rod projecting from said piston through a bore in one end of saidcylinder, and a bushingrestrictor contained in said bore surroundingsaid rod, said bushing-restrictor comprising a sleeve having a pluralityof axially spaced annular grooves in its outer periphery, the landswhich define said grooves therebetween having a close sliding fit insaid bore, and axial slots extending through said lands, said axialslots through adjacent ones of said lands being circumferentially offsetfrom each other and of a size to permit a small portion of the fluidcontained in the rod end of said cylinder to circulate through andaround said grooves before discharging to the adjacent groove forcooling said rod end, the inner end of said sleeve having an outerdiameter which is slightly less than the inner diameter of said bore toprovide a slight diametral clearance which acts as an edge filter forpermitting the fluid in the rod end of said cylinder to pass into theadjacent groove in said sleeve while restricting the passage of anylarge contaminants contained in the fluid, said sleeve having anadditional groove adjacent said inner end which is slightly deeper thansaid plurality of axially spaced annular grooves for receiving the fluidpassing through said diametrical clearance, said sleeve having stillanother groove adjacent the outer end of said sleeve which is axiallylonger than said plurality of axially spaced annular grooves, and radialholes extending through said sleeve communicating with said axiallylonger groove for lubricatIng said rod.
 2. A fluid actuator comprisingan actuator cylinder, a piston axially reciprocable in said cylinder,means for permitting fluid to flow into and out of opposite ends of saidcylinder for reciprocating said piston, a rod projecting from saidpiston through a bore in one end of said cylinder, and abushing-restrictor contained in said bore surrounding said rod, saidbushing-restrictor comprising a sleeve having a plurality of axiallyspaced annular grooves in its outer periphery, the lands which definesaid grooves therebetween having a close sliding fit in said bore, axialslots extending through said lands of a size to permit a small portionof the fluid contained in the rod end of said cylinder to flow throughand around said grooves for cooling said rod end, and radial holesextending through said sleeve communicating with one of said grooves forlubricating said rod.
 3. A fluid actuator comprising an actuatorcylinder, a piston axially reciprocable in said cylinder, means forpermitting fluid to flow into and out of opposite ends of said cylinderfor reciprocating said piston, a rod projecting from said piston througha bore in one end of said cylinder, and a bushing-restrictor containedin said bore surrounding said rod, said bushing-restrictor comprising asleeve having a plurality of axially spaced annular grooves in its outerperiphery, the lands which define said grooves therebetween having aclose sliding fit in said bore, said sleeve having another grooveadjacent the inner end thereof in direct fluid communication with therod end of said cylinder, and axial slots extending through said landsbetween said axially spaced annular grooves, said axial slots throughadjacent ones of said lands being circumferentially offset from eachother and of a size to permit a small portion of the fluid entering saidadditional groove adjacent the inner end of said sleeve from the rod endof said cylinder to flow through and around said grooves beforedischarging to the adjacent groove for cooling said rod end.
 4. Thefluid actuator of claim 3 wherein said axial slots through alternateones of said lands are located on opposite sides of said sleevediametrically opposite each other to maximize the circulation of fluidthrough said annular grooves.
 5. The fluid actuator of claim 3 whereinthe inner end of said sleeve has an outer diameter which is slightlyless than the inner diameter of said bore to provide a slight diametralclearance which acts as an edge filter for permitting the fluid in therod end of said cylinder to pass into the groove adjacent the inner endof said sleeve while restricting the passage of any large contaminantscontained in the fluid.
 6. The fluid actuator of claim 5 wherein saidgroove adjacent the inner end of said sleeve is slightly deeper thansaid axially spaced annular grooves for receiving the fluid passingthrough said diametral clearance.
 7. The fluid actuator of claim 3further comprising a packing, and means for retaining said packingwithin said bore outwardly of said sleeve, the outer end of said sleevehaving an out-turned flange thereon projecting radially outwardly beyondsaid lands, and said bore having a shoulder adapted to be engaged bysaid out-turned flange to prevent said bushing-restrictor from beingforced into said cylinder by said packing.
 8. The fluid actuator ofclaim 7 wherein said bushing-restrictor is substantially free-floatingwithin said bore, whereby the fluid in said rod end of said cylinderacting on said bushing-restrictor urges said bushing-restrictor towardsaid packing to compress the same and thus prevent loosening of thepacking and leakage therepast.
 9. The fluid actuator of claim 3 whereinsaid sleeve is substantially imperforate.
 10. The fluid actuator ofclaim 5 wherein said diametrical clearance is approximately 0.004 inch.11. The fluid actuator of claim 2 wherein said one groove is adjacentthe outer end of said sleeve.